Finding out the molecular mechanisms that coordinate cell adhesion and migration is important for our understanding of how normal embryonic development proceeds. Disruption of Eph-receptor signaling dependent morphogenetic processes results in abnormal migration to midline of ventral neuroblasts in C. elegans, similar to abnormalities observed in neural tube formation in vertebrates. I will investigate the role of cell-cell interactions in collective migration of ventral neuroblasts through laser ablation, drug treatments, and whole embryo lineaging. Hence, this proposal addresses the following specific aims: 1. Develop software that integrates lineaging, gene expression, and morphogenetic analysis in C. elegans to automatically construct 4-D atlases of embryogenesis. 2. Define cells and mechanisms for collective migration of ventral neuroblasts. 3. Analysis of the role of a Toll-like receptor in C. elegans morphogenesis. The research will contribute to the scientific community a tool to study morphogenesis in model organisms used in developmental biology. It will also lead to a better understanding of adhesion pathways that are critical for nervous system development in the model organism C- elegans. The results of this research will enhance our understanding of molecular pathways critical for nervous system development during human embryogenesis. Mutations affecting these pathways lead to developmental abnormalities and malformations. Knowledge of the inner workings of these pathways will help with designing therapeutics for ameliorating these conditions.